Three-prong back with positioning prong



FIG. 1 is a front perspective view of a three-prong back with positioning prong showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is an enlarged top plan view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a left side elevational view thereof;

FIG. 7 is a right side elevational view thereof;

FIG. 8 is a front perspective view thereof;

FIG. 9 is a cross-sectional view thereof, taken along line 9—9 in FIG. 8;

FIG. 10 is a front perspective view of a second embodiment of a three-prong back with positioning prong showing my new design;

FIG. 11 is a rear perspective view thereof;

FIG. 12 is an enlarged top plan view thereof;

FIG. 13 is a front elevational view thereof;

FIG. 14 is a bottom plan view thereof;

FIG. 15 is a left side elevational view thereof;

FIG. 16 is a right side elevational view thereof;

FIG. 17 is a front perspective view thereof; and,

FIG. 18 is a cross-sectional view thereof, taken along line 18—18 in FIG. 17.

The broken lines showing environmental structure in FIGS. 8, 9, 17 and 18 are for illustrative purposes only and form no part of the claimed design. 

I claim the ornamental design for the three-prong back with positioning prong, as shown and described. 